1. Field of the Invention (Technical Field)
The present invention relates to a power tool shield and guiding apparatus.
2. Background Art
Stationary power tools normally have cutting and shaping blades protruding through a table top. These tools, for example, table saws, shapers, inverted routers, surface planers, and bandsaws, normally cut or shape a work piece or stock which the operator pushes directly at the protruding blade. Normally, a guide fence to one side of the table, and projecting vertically from the table, guides the work piece. In addition to being pushed toward the blade, a work piece must also be pressed downwardly and laterally to maintain engagement with both the table top and the guide fence.
Safety, of course, is the primary concern in the use of such devices. If the work piece binds against the back of the blade, for example, "kickback" may occur, hurling the work piece towards the operator. Also of great concern is the possibility of the operator directly contacting the protruding blade, with possibly disastrous consequences.
Numerous safety devices have been proposed in the prior art. Blade guards shield the operator from the blade; they frequently also are inconveniently located, inhibit visibility, and require accessory equipment to be fully effective. Hold-down devices force the stock snugly against the table, thereby purportedly preventing "kickback." Such devices may also be inconvenient, require accessory devices such as guards, and interfere with the use of push sticks and guards when cutting narrow work pieces. "Tablesaw Safety Devices," by Robinson (Fine Woodworking, March/April 1990, pp. 84-88), discusses various prior art guards and hold-down devices.
U.S. Pat. No. 1,712,825, to Klehm, entitled Saw Guard, discloses a cantilevered guard shielding a rotary blade. Klehm, however, lacks disclosure regarding hold-down devices and is extremely expensive.
U.S. Pat. No. 2,593,596, to Olson, entitled Circular Saw Guard, likewise lacks a hold-down device, as well as lateral pressure against the fence. The guard must be removed during certain sawing operations such as dadoing, shaping, and narrow cuts. Measuring, positioning, and aligning the rip fence are difficult with this guard in position; ripping, particularly angled rip cuts, are also rendered difficult with the guard in position.
U.S. Pat. No. 4,403,534, to Altendorf, et al., entitled Movable Protective Hood for Power Tool of a Work Tool Machine discloses a guard with a vacuum hood which also lacks a hold-down device.
U.S. Pat. No. 4,096,789, to Blessinger, entitled Saw Guard, likewise lacks hold-down devices, does not prevent "kickback," and provides neither vertical nor lateral pressure on the work piece.